So, it seems that variations in the NOD2/CARD15 gene make cattle more susceptible to infection with Mycobacterium avium subspecies paratuberculosis, as well as making humans more susceptible to Crohn’s Disease.

It appears that some Azathioprine and 6-MP, which are used for the treatment of Crohn’s Disease, and whose mechanism of action is currently unknown, have antibiotic activity against Mycobacterium avium subspecies paratuberculosis (MAP).

As noted by the authors, “These data may partially explain the paradoxical response of Crohn’s disease patients infected with M. paratuberculosis to treatment with immunosuppressive thiopurine drugs i.e. they do not worsen with anti-inflammatory treatment as would be expected with a microbial etiologic pathogen.”
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The abstracts from the Ninth International Colloquium on Paratuberculosis (9ICP), which I attended in Tsukuba, Japan, have been published online.

As with previous ICP, the number of papers presented on the relationship between Crohn’s Disease and Mycobacterium Paratuberculosis has grown, as knowledge of this complex organism and its potential to cause disease in humans, has grown.

I’ve just returned from Copenhagen, Denmark, where I attended the 8th International Colloquium on Paratuberculosis (at considerable personal expense: Copenhagen is EXPENSIVE!)

Current thinking among researchers in the field is that MAP itself is mostly not the culprit in the tissue damage. MAP’s role is to initiate an inflammatory response in the bowel, through some unknown process/antigen/inflammatory-pathway. This immune response results in inflammation of bowel tissue, whereby the cells of the intestine physically separate, to allow immune cells, primarily macrophages and CD4 + CD8 T-cells, to reach the site of infection. This leads to “leaky gut” syndrome , which permits the contents of the bowel (most accurately described as being similar to the contents of a sewer), to leak through the bowel wall, resulting in a *massive* inflammatory response against the many microbes present in the fecal stream.

The researchers describe the case of a man who was diagnosed as having Crohn’s Disease. He tested positive (by PCR) for mycobacterium avium paratuberculosis (MAP) infection, was treated with an anti-paratuberculosis antibiotic regimen, and his health improved (after a period of suffering from a “flu-like syndrome”, a common problem in CD when treated with anti-paratuberculosis antibiotics).

I want to draw your attention to a recent epidemiological study from Wisconsin, which studied the epidemiology of both Crohn’s Disease, and IBD in general, in children in the state of Wisconsin. You can read an abstract of the study here

Researchers at the University of Minnesota, in conjunction with researchers from the United States Department of Agriculture, have completed their work on the sequencing of the genome of MAP. Their press release can be found here